Investigation and enhancement of the adhesion properties for an optimized lamination of DE multilayer stack-transducers

Abstract

Transducers based on dielectric elastomers (DE) have gained a lot of attention within the last few years. Due to an electric field, the elastic material covered with electrodes on both opposing sides deforms. This effect is applicable for generator and actuator applications. To increase the absolute deformation multilayer, DE transducers are used. In order to transmit tensile forces, the adhesion between each layer has to be sufficiently high. Therefore, the adhesion between the layers and between the layer and the electrode are investigated within this publication. Different adhesion theories are presented and assessed in terms of effectiveness and their influence on electromechanical characteristics. To determine the parameters influencing the adhesion, the theory according to Johnson, Kendall and Roberts (JKR-theory) is studied and an approach to increase the adhesion of rough surfaces is deduced. Furthermore, methods to enhance the adhesion are presented and executed. In particular, a surface plasma treatment is conducted and the influence of different electrode composites is investigated with respect to their bonding properties of the multilayer DE composite. To assess the enhancement capability, T-peel tests are carried out proving the peel resistance against delamination. Besides that, surface resistance and dielectric breakdown strength are analyzed to investigate the influence of surface treatment on the electric properties. Finally, a conclusion summarizes the obtained results.

Dielectric breakdown strength measurements with silicone-based single-layer dielectric elastomer transducers

“…Considering the simplified analytical calculation from section 2, measurement uncertainties, environmental influences etc, the measured values are within the range of the calculated nominal dielectric breakdown strength of 90.3 V μm −1 (vertical thick grey line in the Weibull plot). A previous breakdown test with Elastosil ® Film2030 has obtained a similar breakdown strength which confirms the present results [27]. However, the DET test samples measured with AC500Hz show a significant higher electrical breakdown strength with a characteristic valueα=124.9 V μm −1 than the DETs measured with DC and AC125 Hz.…”

“…But in contrast to the rigid electrodes in the breakdown measurement setups, the electrodes in DETs are compliant and able to deform with the elastic dielectric during operation of the DET. Only few works have addressed this difference until now with breakdown measurements using fabricated DETs [23,27,28]. But no systematic investigation of the dielectric breakdown strength of DETs with compliant electrodes have been reported.…”

Improving the performance of dielectric-elastomer actuators at elevated operating temperatures by means of thermal softening

“…As schematically depicted in figure 1, when an external voltage is applied to the electrodes, electrostatic forces are generated between the electrode charges and an electrostatic pressure, the so-called Maxwell stress squeezes the elastomer in thickness direction forcing the entire device to expand in the planar area [11]. Electrical energy is thus converted into elastic or mechanical energy.…”